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The purpose of our rating lists is provide engine authors and enthusiasts with a general comparison of engine strength. We also provide other data that could be of interest.For various reasons, there may be some engines that do not appear on our lists, therefore it is useful to look at other rating lists as well as ours. The inclusion or exclusion of engines in our lists should not be taken as our group making a statement about their legality or status. However, where there is controversy surrounding an engine in our lists, we have indicated this.We test chess engines for our own enjoyment and receive no payment for doing so.

Please note that the three lists are often updated separately to each other.The links given in each update report will give you the currently up to date lists.

The links to the various rating lists can be found just beneath the default Best Versions list (as in this screenshot). Specific 32-bit rating lists are denoted as such to the right of the default list in each category. The default lists contain the 64-bit engines.

Our 40 moves in 40 minutes repeating and 40 moves in 4 minutes repeating are both adjusted to the AMD64 X2 4600+ (2.4GHz).

Be aware that in the early stages of testing, an engine's rating can often fluctuate a lot.It is strongly advised to look at the many other rating lists available in order to get a more accurate overall picture of an engine's rating relative to others.

The LOS (likelihood of superiority) stats to the right hand side of each rating list tell you the likelihood in percentage terms of each engine being superior to the engine directly below them.

All games are available for download by engine, by month or by ECO code, but you will need to remove the .live from the links if you wish to access these (for example http://computerchess.org.uk/ccrl/4040 ). The download databases by month or ECO code are only updated monthly, but the total games database in its entirety is always available.The current ELO ratings are saved in all game databases for those engines that have 200 games or more.

Clicking on an engine name will give details as to opponents played plus homepage links where applicable.

Custom lists of engines can be selected for comparison.

An openings report page lists the number of games played by ECO codes with draw percentage and White win percentage. Clicking on a column heading will sort the list by that column.

I can't speak for the other testers, but I'm undecided about Strelka 5 at present. The comments below have put me in two minds.

Firstly, Robert Houdart's response to Osipov having sent him the source code:Your file has arrived now.I'm not going to make any other comment than that it's quite hilarious, and that Richard Vida's version was better Smile.

And secondly, Robert's response at seeing Strelka included in the CEGT list:One reason for the difference in evaluations is that Jury (purposely?) forgot to divide the output by 2 to obtain centipawns - Houdini uses 1/200 pawn units internally.

Seeing the results published on CEGT, I actually feel some sympathy for Norman's complaints about rating lists. If Strelka is readily adopted by the CEGT people, why continue to exclude Ivanhoe or Fire?

With Strelka we have an engine that is, by its author's admission, the direct result of reverse engineering Houdini 1.5. Unsurprisingly it produces identical results in move choices (see the similarity diagram) and in Elo strength (see the CEGT results).

Personally I don't mind Houdini (in whatever form) occupying all the upper ranks of the rating lists, but I'm not sure it adds to the rating list's relevance Wink.

Fritz 13, Chiron 1.1, Tornado 4.80 and many other engines still need to be added or established in our lists, so there's always plenty to do meanwhile.